Surgery, Biopsies and Chemotherapeutics Flashcards
Describe Marek disease virus
- Oncogenic herpesvirus
- Tumours derived from T lymphocytes
What are the consequences on immune cells due to Marek’s disease virus?
- B lymphocytes and macrophages are killed
- T-lymphocytes are activated to proliferate and form tumour
Outline the control of Marek’s disease virus
- Disinfection
- Biosecurity
- All-in, all-out management
- Vaccination
- New strains emerging each more virulent, so new vaccines required at each new mutation
Why is diagnosis and staging important prior to treatment of a tumour?
- Extent of treatment depends on tumour type and stage
- With regards to surgery, need to know the surgical margins that will be required
What are the general principles of biopsy?
- Handle tissue gently
- Position site within probable surgical or radiotherapy field
- Should be as small as possible, position so as to not increase size of treatment area
- Sample from different areas of lesion, including junction of normal-abnormal tissue
- Avoid local dissemination of neoplastic tissue
- So not breach anatomical planes
What are the indications for incision biopsy?
- When mass will not exfoliate well for FNA, not amenable to core biopsy
- When cytology or core biopsy results are non-diagnostic
- Lack of core biopsy equipment
- If is more likely to achieve diagnosis and grade
What are disadvantages of excisional biopsy?
- Surgical margins unknown, risky
What are the advantages of an excisional biopsy?
- May be cost saving in some cases
- Diagnosis and treatment are possible within single surgery
- Good where diagnosis of tumour type and grade will not affect surgical approach
What are the roles of oncological surgery?
- Prophylactic e.g. ovariohysterectomy prior to 1st season, cryptorchid testicles
- Diagnosis and staging
- Definitive excision
- Palliative surgery
- Cytoreduction in order to treat with adjunctive methods
- Management of oncologic emergencies
- Surgery for supportive therapy
- Treatment of metastatic disease
What are the 3 possible aims of surgical excision of a tumour?
- Curative
- Cytoreductive
- Palliative
What is meant by palliative surgical excision of a tumour?
Where removal of a tumour that is causing other problems e.g. blocking nasal passages
Compare primary surgery and revisions with regards to success in treating tumours
- Primary best chance for cure
- Untreated tumours have more normal surrounding anatomy facilitating surgical removal
- Recurrent tumours may have seeded to previously unaffected areas, need wider, deeper resection
What is meant by surgical dose?
How much surgery
What is marginal excision?
- Excision immediately outside the pseudocapsule
- Are leaving behind microscopic volumes of tumour
What is a wide excision?
Removal of tumour with complete margins of normal tissue in all directions, so local recurrence is unlikely
What tissues are good natural barriers to spread of cancer cells?
Collagen rich, relatively avascular tissues e.g. fascia, ligaments, tendons and cartilage
What tissues are poor barriers to spread of cancer?
Fat, subcutaneous tissue, muscle, other parenchymatous organs
What is radical excision?
Removal of entire anatomical structure or compartment continuing the tumour e.g. limb amputation, mastectomy. Local recurrence is unlikely
What is meant by lateral and deep margins of a tumour?
- Lateral are the margins around the visible lesion (ruler used)
- Deep margins are the margins below the visible lesion
In what lesions is a needle only FNA useful?
Soft masses and lymph nodes, want to avoid destroying fragile cells with suction
In what lesions is a continuous suction FNA useful?
Firm masses e.g. firbosarcomas as these do no exfoliate well
In what lesions is an intermittent suction FNA useful?
Small masses where it is not possible to redirect the needle without exiting the mass
What size needle should be used for FNAs?
23 gauge
What are the indications for a tru-cut biopsy?
- Superficial masses (incl. lymph nodes) that can be palpated and stabilised
- Internal organs that can be safely accessed via ultrasound guidance
